RU171128U1 - DEVICE FOR FIXING AN EXTENDABLE WALL ON A CYLINDER CATHETER WITH INTERNAL THERMOSTATING - Google Patents

Abstract

The utility model relates to medical equipment, namely to intravascular stents for implantation in a living organism, which are expanded using an inflated balloon catheter, and in particular to devices for fixing an expandable stent on a balloon catheter with internal temperature control. The device includes a plate with a slot, a thermostatic chamber mounted on the plate, a flexible tape passed through the slot to form a loop on one side of the plate in the thermostatic chamber for placement inside the stent loop with the catheter inside it and the second loop on the other side of the plate, a tape tension means, made in the form of a drive shaft placed in the second loop with an axis of rotation parallel to the horizontal plane of the plate, and a drive made with the possibility of linear movement of the axis perpendicular to the horizon the entire plane of the plate with the transmission of torque to the drive shaft. In this case, the longitudinal size of the slot is equal to or greater than the width of the tape, and the transverse is more than two thicknesses of the tape, but less than the sum of two thicknesses and the minimum cross-sectional size of the lamellas. Using the utility model will ensure uniform compression of the stent with less likelihood of damage to the stent during compression compared to peers and at the same time simplifying the implementation of the specified compression.

Description

APPLICATION AREA

The utility model relates to medical equipment, namely, to intravascular stents for implantation in a living organism, which are expanded using an inflated balloon catheter, and in particular to devices for installing and securing a stent on a balloon catheter.

BACKGROUND

The prior art device for securing an expandable stent on a balloon catheter made in the form of a U-shaped frame equipped with a set of flat loops in which a balloon catheter with a stent is placed on it (JP 2000245847 A, publ. 12.09.2000). The device is equipped with a means for tightening the loops when moving which the loops are tightened on the stent and the stent is fixed on the catheter. A disadvantage of the known device is that the loops are made at intervals, resulting in an uneven application of compression forces to the stent, and, as a result, the outer surface of the stent becomes wavy in nature, which affects the movement of the stent through the blood vessel.

Also known is a device for installing and securing a stent on a balloon catheter (RU 2190374 C2, publ. 10.10.2002). The device comprises first and second clamping parts mounted with the ability to move in the direction towards each other and in the opposite direction from each other. In the clamping parts there are recesses forming a channel for receiving a tube for crimping the stent. A stent is passed into the longitudinal opening of the tube holding the stent, and then a balloon catheter is passed into the longitudinal opening of the stent. The first and second clamping parts are moved towards each other and create pressure on the outer surface of the tube pressing the stent, causing the inner diameter of the longitudinal hole to become smaller and create pressure on the outer surface of the stent and press the stent against the balloon.

A disadvantage of the known device is that as a result of the stent being fixed on the balloon catheter, it takes the form of an ellipse in cross section, which affects the movement of the stent through the blood vessel. This is due to the fact that the recesses in the clamping parts have a fixed shape and as a result of their rapprochement do not provide uniform deformation of the stent in the direction of its longitudinal axis.

The closest analogue is a device for crimping a stent on a balloon catheter (US 6141855 A, 11/7/2000). The device is a plate with a slot, a flexible tape passed through the slot to form a loop on one side of the plate for placement inside the stent loop with a catheter inside it, and a means of tensioning the tape on the other side of the plate. The means for tensioning can be made in the form of a spring or a pneumatic cylinder.

A disadvantage of the known device is the inconvenience of use due to the low level of mechanization. In particular, in the description (description column 4, lines 32-37), it is indicated that to secure the stent on the catheter, after the first compression, it is necessary to loosen the tension of the loop covering the stent, turn the stent-catheter assembly and tighten again and repeat this operation repeatedly.

Thus, existing known methods of installing and securing the stent on a balloon catheter lead to uneven deformation of the stent, which can create protrusions on the stent, subsequently leading to injury to the patient.

Thus, an important task is to create a device that would allow quick and easy fixation of the stent on the expandable balloon of the balloon catheter without causing uneven deformation or weakening of the stent.

DISCLOSURE OF A USEFUL MODEL

The objective of the utility model is to create a device for fixing an expandable stent on a balloon catheter, which allows for uniform compression of the stent and simplifies the procedure for implementing compression.

The technical result achieved when using the utility model is to increase the uniformity of compression of the stent.

The technical result is achieved by the fact that the device for fixing the expandable stent on the balloon catheter with internal temperature control includes a plate with a slot, a thermostatic chamber mounted on the plate, a flexible tape passed through the slot to form a loop on one side of the plate in a thermostatic chamber for placement inside the stent loop with a catheter inside it and a second loop on the other side of the plate, a belt tensioner made in the form of a drive shaft placed in the second loop with the axis of rotation, steam the horizontal horizontal plane of the plate, and the drive, made with the possibility of linear movement of the axis perpendicular to the horizontal plane of the plate with the transmission of torque to the drive shaft, while the longitudinal size of the slot is equal to or greater than the width of the tape, and the transverse is more than two thicknesses of the tape, but less than the sum of two thicknesses and minimum cross-sectional size of lamellas.

In addition, the surface of the shaft is made of a material that provides a coefficient of sliding friction of a pair of material of the shaft - the material of the tape is not lower than 0.3

In this case, the stent is not a tube with a continuous surface, but a lattice or mesh. With a somewhat more detailed description, we can say that the stent is "cut out" or cut out, for example, using a laser, from a tube with a continuous surface, and at the same time separate, although interconnected, bearing segments are formed that make up the frame. A device for crimping an expandable stent on a balloon catheter can be applied to stents with any type of design and manufacturing method - wire (made from a single wire), tubular (made from a cylindrical tube), ring (made from separate links) or mesh (in the form of a braided mesh).

Bearing segments are understood to mean separate strong elastic segments that make up the stent frame, which are connected to each other at the intersection points or nodes, forming a flexible and elastic structure of the stent, allowing it to expand or unfold.

The term "lamella stent" or "stratum" in this application refers to a single element of the frame of the stent of a straight or rounded shape, limited to the bearing segments and nodes of their intersection.

The term "cross section" of the lamellas of the wall in this application is understood to mean the thickness of the stent. The cross-sectional size of the element can vary in the range from 80 to 160 microns.

The looping of the tape with the formation of the second loop on the other side of the plate, and the tape tension means in the form of a shaft placed in the second loop with the axis of rotation parallel to the plane of the plate and equipped with a drive for its rotation and movement perpendicular to its axis of rotation, allows uniform compression of the stent while simplifying the procedure for its implementation. The proposed device eliminates the need for several operations of compression of the stent on the catheter. Indeed, in the proposed device, the stent-catheter assembly is placed in the loop, and simultaneously with the tightening of the loop, the assembly rotates, i.e. there is no need to turn the assembly manually.

The flexible tape can be made of any suitable material based on the low degree of adhesion to the stent material, in particular, the flexible tape can be made of polyamide, fluoroplast, polyethylene terephthalate and so on.

Placing a loop with a catheter in a thermostatically controlled chamber allows the stent material to be heated to the range of melting temperatures characteristic of the selected stent material, at which, due to thermal pressure, the polymer crystallinity decreases and the polymer transitions to a viscous or plastic state, which leads to a reduction in mechanical stress connections and excesses of strata. Thus, the likelihood of damage to the stent during compression is reduced.

Since the assembly rotates in close contact with the slot through which the tape is passed, there is a risk that the assembly may jam - tighten individual stent lamellas into the slot. Therefore, the transverse dimension must be greater than two thicknesses of the tape, but less than the sum of the two thicknesses and the minimum cross-sectional size of the lamellas. And so that the tape freely, without creasing, moves in the slot, the longitudinal size of the slot must be equal to or greater than the width of the tape.

BRIEF DESCRIPTION OF THE DRAWINGS

Details, features, and also advantages of the present utility model follow from the following description of the claimed technical solution using the drawing, which shows a schematic diagram of the proposed device.

In the figure, the numbers indicate the following positions:

1 - a rigid plate, 2 - a slot in the plate, 3 - a flexible tape, 4 - a loop formed by a flexible tape for placement of a balloon catheter with a stent, 5 - a stent, 6 - a balloon catheter, 7 - a thermostatic chamber, 8 - a loop formed by a flexible tape to accommodate the drive, 9 - drive.

IMPLEMENTATION OF A USEFUL MODEL

The essence of the claimed utility model is illustrated by an example of its implementation and the drawing, which schematically shows the device (cross section)

A device for fixing an expandable stent on a balloon catheter with internal temperature control consists of a body in which a plate 1 with a slot 2 is placed, which is fixed by at least one end element on the body using known assembly operations, for example, screwing or welding and the like. For clarity, mounting hardware is omitted from the drawing.

A thermostat is mechanically attached to the upper horizontal base of the plate, which is a device with a heating (thermostatically controlled) chamber 7, in which the set temperature conditions can be installed and maintained for a long time (from room temperature to 200 ° C). The heating chamber 7 is made in the form of a tunnel with a rear wall and a front cover (door) that opens vertically.

The heating chamber is mechanically fixed on the upper horizontal base of the plate 1 coaxially with a balloon catheter 6 with a tape 3 placed inside. On the side walls of the heating chamber 7 there are fixed heat electric heaters (TENs), which are included in a single electric circuit with a temperature meter-regulator (for example, the Aries of TPM201 temperature regulator ) Perforations and through holes are made in the tunnel body below the level of the heaters.

The temperature meter is mounted in the door of the heating chamber or in one of the side walls of the heating chamber.

The thermostat control unit is made in a separate housing.

On the housing below the rigid plate 1, an axis is fixed on which the drive shaft is mounted. The axis is connected to the drive 9, performing a linear movement of the axis with the transmission of torque to the drive shaft. The axis is parallel to the horizontal plane of the plate 1, while the linear movement of the axis is perpendicular to the horizontal plane of the plate 1.

As the drive 9, performing linear movement of the axis with the transmission of torque to the drive shaft, for example, spline guides, which are a spline shaft and a nut, consisting of a cylindrical body, a separator, o-rings and rolling elements (balls) can be used.

The source material in the form of a flexible tape 3 is sent from the drive shaft through the slot of the plate, then to the stent 5 with a balloon catheter 6, rounding it and forming a loop part of the tract. Then the flexible tape is tucked into the slot. After connecting the ends of the tape, its predetermined tension is ensured by a linear drive. The stent 5 with a balloon catheter 6 with an envelope around the specified assembly tape is located in the heating chamber 7 of the thermostat without touching the side or rear walls of the heating chamber.

The surface of the shaft is made of a material that provides a coefficient of sliding friction of the pair of material of the shaft - the material of the tape is not lower than 0.3.

In this case, the longitudinal size of the slot 2 is equal to or greater than the width of the tape 3, and the transverse dimension is greater than two thicknesses of the tape, but less than the sum of two thicknesses and the minimum size of the cross section of the lamellas (not shown in the drawing).

In laboratory conditions, these elements are mounted on a vertical tripod at different levels. All components and parts of the device can be selected from among those known from the prior art.

The device operates as follows.

A stent 5 is put on the balloon catheter 6 and placed inside the loop 4 of the flexible tape 3 on one side of the plate 1.

When starting the installation using the controller of the control unit, the thermostat 7 is turned on and the required temperature regime of the heating chamber is set, depending on the material of manufacture of the stent, power is supplied to the drive 9.

The injected air blows through the heaters, and through the perforations is supplied by a distributed stream into the tunnel, where the required temperature is maintained. After uniform heating of the stent-catheter assembly to the softening temperature of the stent material due to thermal conductivity, the stent material loses its elasticity, and the device is ready to pressure test the stent on a catheter placed inside the tape.

Upon reaching the indicated temperature displayed on the indicator, the operator turns on the rotation drive located in the loop 8 of the shaft 9 and its movement perpendicular to its axis of rotation.

The speed of movement of the tape is determined by the speed of rotation of the drive shaft on the axis, the rotation moment to which is transmitted by the drive 9. The tension force of the tape 3, necessary for uniform deposition of the stent 5 on the balloon catheter 6, is selected experimentally and set by the drive performing linear axis movement. Accordingly, the greater the distance from the plate 1 to the axis, the stronger the interference of the flexible tape.

The loop 4 is tightened, tightly covering the stent 5 with a balloon catheter 6 inside it, and since the tape 3 is driven by the shaft 9, the assembly "stent catheter" begins to rotate. The heated stent under the action of the force created by the female tape during rotation of the assembly tightly fits the balloon catheter 6. The rotation of the assembly while maintaining a constant softening temperature of the stent material continues until the desired nominal diameter of the stent, determined by the initial dimensions of the catheter, is reached. Next, turn off the power to the drive. Information on the softening temperatures of different materials of the stent are given below in table 1.

Then, without removing the tension of the tape, the assembly is cooled to a temperature of 23-25 ° C. At the same time, the stent material restores its viscoelastic properties, but remains tightly compressed on the balloon catheter. The tight compression of the stent on the balloon expandable catheter during cooling is necessary to maintain the shape of the stent without deformation.

After the stent is cooled to the required temperature, the tape is cut off and the assembly is removed from the thermostatically controlled chamber.

Thus, uniform force is applied to all points of the stent surface and the stent is securely fixed to the catheter.

The uniform movement of the flexible tape and the uniform stent upset on the balloon catheter provides the drive.

Reducing the likelihood of damage to the stent during compression, which also contributes to the uniform deposition of the stent on the balloon catheter, is achieved by heating and cooling the tape material in the heating chamber of the thermostat.

The loop mechanism of movement of a flexible tape, in one loop of which there is a stent with a balloon catheter, in the other - the drive shaft of the belt tensioner with a drive that linearly moves the axis with the transmission of torque to the drive shaft, provides a smooth adjustment of the speed of continuous rotation of the balloon catheter with a stent in the loop at a certain degree of tension and, consequently, the uniformity of compression of the stent on the catheter, and also reduces the degree of mechanization of the installation.

Providing certain ratios of the geometrical parameters of the slot in a rigid plate with the width and thickness of the tape avoids uneven deformation of the stent when it is crimped on a balloon catheter, which is a reliable sliding support.

Claims (7)

1. A device for fixing an expandable stent on a balloon catheter with internal temperature control, containing a plate with a slot, a thermostatic chamber mounted on the stove, a flexible tape passed through the slot to form a loop on one side of the plate in a thermostatically controlled chamber for placement inside the stent loop with a catheter inside it and a second loop on the other side of the plate, belt tensioning means in the form of a drive shaft placed in a second loop with a rotation axis parallel to the horizontal plane of the plate and a drive configured to linearly move the axis perpendicular to the horizontal plane of the plate with transmitting torque to the drive shaft, while the longitudinal size of the slot is equal to or greater than the width of the tape, and the transverse is more than two thicknesses of the tape, but less than the sum of two thicknesses and the minimum cross-sectional size of the lamellas. 2. The device according to claim 1, characterized in that the material of the flexible tape is polyamide, or fluoroplast, or polyethylene terephthalate. 3. The device according to claim 1, characterized in that the shaft surface is made of a material that provides a sliding friction coefficient of a pair of shaft material — tape material not lower than 0.3.

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